<!--
    列表结构可以通过v-for指令结合数据生成

    v-on结合事件修饰符可以对事件进行限制，比如.enter

    v-on在绑定事件时可以传递自定义参数

    通过v-model可以快速的设置和获取表单元素的值

    基于数据的开发方式

-->

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>小黑记事本</title>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8" />
    <meta name="robots" content="noindex, nofollow" />
    <meta name="googlebot" content="noindex, nofollow" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link rel="stylesheet" type="text/css" href="./css/index.css" />
</head>
<body>
        <!-- 主体区域 -->
        <section id="todoapp">
            <!-- 输入框 -->
            <header class="header">
              <h1>小黑记事本</h1>
              <input autofocus="autofocus" autocomplete="off" placeholder="请输入任务"
                class="new-todo" v-model="addValue" @keyup.enter="add(addValue)"/>
            </header>
            <!-- 列表区域 -->
            <section class="main">
              <ul class="todo-list">
                <li class="todo" v-for="(item,index) in list">
                  <div class="view">
                    <span class="index">{{index+1}}.</span> <label>{{item}}</label>
                    <button class="destroy" @click="remove(index)"></button>
                  </div>
                </li>
              </ul>
            </section>
            <!-- 统计和清空 -->
            <footer class="footer">
              <span class="todo-count" v-if="list.length!=0"> <strong>{{list.length}}</strong> items left </span>
              <button class="clear-completed" @click="clear" v-show="list.length!=0">
                Clear
              </button>
            </footer>
          </section>
          <!-- 底部 -->
          <footer class="info">
            <p>
              <a href="http://www.itheima.com/"
                ><img src="./img/black.png" alt=""
              /></a>
            </p>
          </footer>
          <!-- 开发环境版本，包含了有帮助的命令行警告 -->
          <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
          <script>
              var app = new Vue({
                  el:"#todoapp",
                  data:{
                      list:["吃饭","睡觉","学习"],
                      addValue:"打游戏"
                  },
                  methods:{
                    add:function(value){
                        this.list.push(value)
                    },
                    remove:function(index){
                        this.list.splice(index,1)
                    },
                    clear:function(){
                        this.list=[]
                    }
                  }
              })
          </script>
</body>
</html>